1. Field of the Invention
The present invention relates generally to the field of attachment systems. More particularly, it concerns systems for attaching one or more explosive device(s) to a flexible linear support, related methods and devices, and methods of using the charge assemblies thus produced.
2. Description of Related Art
An Anti-Personnel Obstacle Breaching System (APOBS) has been under development for the United States Marine Corps by the Naval Surface Warfare Center (NSWC). The system contains one Rocket Motor, a Line Charge Assembly (LCA) which contains detonating cord and 108 evenly spaced grenades, a single or multiple fuze assemblies, a parachute assembly, two backpack sets, and a shipping container. The APOBS system is designed to clear a safe lane (approximately 0.6-2.0 meters wide by 45 meters long) through wire obstacles containing anti-personnel landmines.
The current LCA design supports the evenly spaced grenades using two parallel 0.25 inch nylon ropes. The grenades are secured to the ropes via twin metal band clamp assemblies. The ropes are designed to be structural members that carry all of the grenade launch and deceleration loads. In addition, the detonating cord running through the center of each grenade is routed with adequate slack to minimize launch induced tensile loads on the cord, i.e., the rope carries the weight of the grenades, grenade attachments, and detonating cord.
Current system grenade attachment specifications prescribe labor-intensive processes that require highly specified and non-standardized components, numerous calibrations and quality checks, and expensive, one-of-a-kind clamping machines. Structural inadequacies, grenade separation and attachment degradations reducing storage life and performance reliability were noticeable problems during the development phase of the APOBS program. The structural support, spacing, and orientation control for the grenades during deployment and impact has also been an area of ongoing concern.
Though the band clamp attachment approach has been demonstrated to adequately support the grenades during deployments, the overall attachment performance and manufacturing processes have proven to be less than satisfactory. A key design feature of the structural attachment mechanism of the band clamp approach was that the clamps allow the ropes to predictability slip under the bands during deployment (shock) loading (2.0 inch slippage maximum). This predictable energy-absorbing rope slippage provided a shock absorption feature that reduced overall loads throughout the line charge assembly. However, the metal clamp edges tended to cut and fray the rope. In addition, the clamping action tended to pinch the outer layer of the dual braided nylon rope allowing only the inner braid to slip under the band--resulting in all the loads being carried by the damaged outer braid--resulting in premature rope failure.
The grenades are stowed in their backpack containers 90.degree. to the direction of deployment, i.e., the ropes are first pulled perpendicular to the grenade axis. After the initial snatch, the grenades align with the deployment direction because the center of gravity of the grenade is behind the forward clamping band. The highest loads are experienced during the initial snatch, and this loading tends to pull the ropes circumferentially under the bands towards the rope pull side of the grenade. This circumferential slippage misaligns the axis of the grenade with the direction of deployment and reduces the maximum load carrying capability of the attachment.
Therefore, an attachment system that prevents rope fraying and misalignment would, among other factors, increase the performance and load carrying capabilities, and would thus represent a significant advance in the art.